This is our fabled Gem City , whose seemingly inexhaustible mines produce rubies , star rubies , sapphires , cat’s eyes , topaz , amethysts ,zircons ,tourmalines , and moonstones(feldspar) in endless profusion . Visits to watch the treasure come out of the earth can be arranged . The National Gem Museum , Rathnapura , has a good collection ; so do several private museums .